Model thermal emission spectra from Chen et al. (2014) (gray for oxygen- and black for carbon-enhanced chemical compositions). Black body lines for fully efficient (α = 0.25) and inefficient (α = 2/3) circulations are shown by blue lines. The corresponding temperatures are given in the lower right corner. The optical and infrared occultation depths derived in this paper are shown with red dots, and the Spitzer data of Baskin et al. (2013) with yellow dots. The inset zooms in the optical waveband.